Synthesis and characterization of cleavable as will as noncleavable photosensitive heterobifunctional reagents of maximum linking length up to 25 A; the photosensitive group will be phenylazides and N-hydroxysuccinimide or imidate will be the conventional functional groups. Several sulfhydryl specific reagents are also planned. Cleavable reagents will be prepared initially with a disulfide bond, and its position in reagents will be varied in order to increase its stability against potential disulfide exchanges. To synthesize cleavable photosensitive heterobifunctional reagents carrying radioisotopes, in particular at the photosensitive half of the reagents, and to establish ways to label surface receptors with or without permanently crosslinking hormones and receptors. To attach reagents to luteinizing hormone and to characterize activated molecules. To bind the activated hormone to granulosa cells and to identify binding molecules. To determine if binding molecules are receptors. To identify the subunit of receptors, responsible for binding if receptors have a subunit structure. To crosslink hormones activated with radioactive reagents to receptors, to remove the hormones after cleaving a bond in the reagents under mild conditions, leaving behind the radioactive part of the reagents attached to receptors, and to identify receptors on SDS-PAGE. To prepare antisera against receptors isolated on SDS-PAGE and to test if they block the hormone binding to receptors on cells. To isolate receptors on affintiy column of hormones and anti receptors and to compare them with receptors identified on DSD-Page in crosslinking studies. To determine the effect of the length, reaction specificity, and hydrophobicity and hydrophilicity of reagents on crosslinking of activated hormones to receptors.